This application relates to the art of pumps and, more particularly, to pump impellers and inlet filter assemblies. The invention is particularly applicable for use with sump pumps and will be described with specific reference thereto. However, it will be appreciated that many features of the invention have broader aspects and can be used in other types of pumps.
Many sump pumps require seals for minimizing backflow of liquid from the discharge side of the pump back toward the inlet which reduces pump efficiency. It would be desirable to have an essentially sealless sump pump that nevertheless minimizes backflow of liquid from the impeller chamber toward the inlet.
Many sump pumps have filters located very low on the pump housing within the sump and are very difficult to clean without removing the entire pump from the sump. It would be desirable to provide a sump pump with a top mounted filter assembly that is easily accessible for cleaning.
Float operated switches on sump pumps commonly are exposed to damage or may malfunction due to debris. It would be desirable to position a float switch in a protected location where it is not subject to damage or to fouling by debris.
In accordance with the present application, a pump impeller has an annular liquid inlet surrounding the impeller rotational axis. Incoming liquid flows axially through the impeller in an annular stream to the impeller vanes for discharge from a pinched vaneless diffuser and a volute in which the impeller rotates.
In a preferred arrangement, a permanent magnet motor rotor ring is attached to the impeller in surrounding relationship to the annular liquid inlet so that incoming liquid flows through the center of the magnet ring.
The impeller includes a central hub on which the impeller is rotatably mounted. An annular shroud surrounds the hub in outwardly-spaced relationship thereto so that the annular liquid inlet passage is defined between the hub and the annular shroud.
A plurality of circumferentially-spaced vanes extend in a direction outwardly of the hub adjacent the bottom thereof. The hub includes a hub bottom shroud that extends outwardly from the hub beneath the vanes, and the annular shroud extends upwardly above the vanes. A steel ring is molded onto the exterior of the impeller annular shroud, and the annular permanent magnet motor rotor ring is attached to the steel ring.
In accordance with another aspect of the application, a cylindrical filter assembly is provided on the top portion of the pump. A float switch assembly for operating the pump motor is mounted inside of the filter assembly to protect same from damage and to prevent malfunctioning thereof by debris.
The filter assembly includes a perforate cylindrical sheet metal member surrounded by a pleated screen. Top and bottom rings receive top and bottom end portions of the sheet metal member and screen, and the assembly is attached to the pump base by elongated bolts.
It is a principal object of the invention to provide an improved pump impeller.
It is another object of the invention to provide a pump impeller having a permanent magnet motor rotor attached thereto.
It is also an object of the invention to provide an improved filter assembly for a sump pump.
It is an additional object of the invention to provide an improved arrangement for protecting a float switch assembly against damage or fouling by debris.